# Author: Ingo Feinerer

.PCorpus <-
function(x, meta, dmeta, dbcontrol)
    structure(list(content = as.list(x), meta = meta, dmeta = dmeta,
                   dbcontrol = dbcontrol),
              class = c("PCorpus", "Corpus"))

PCorpus <-
function(x,
         readerControl = list(reader = x$defaultreader, language = "en"),
         dbControl = list(dbName = "", dbType = "DB1"))
{
    stopifnot(inherits(x, "Source"))

    readerControl <- prepareReader(readerControl, x$defaultreader)

    if (is.function(readerControl$init))
        readerControl$init()

    if (is.function(readerControl$exit))
        on.exit(readerControl$exit())

    if (!filehash::dbCreate(dbControl$dbName, dbControl$dbType))
        stop("error in creating database")
    db <- filehash::dbInit(dbControl$dbName, dbControl$dbType)

    # Allocate memory in advance if length is known
    tdl <- if (x$length > 0)
        vector("list", as.integer(x$length))
    else
        list()

    counter <- 1
    while (!eoi(x)) {
        x <- stepNext(x)
        elem <- getElem(x)
        id <- if (is.null(x$names) || is.na(x$names))
            as.character(counter)
        else
            x$names[counter]
        doc <- readerControl$reader(elem, readerControl$language, id)
        filehash::dbInsert(db, meta(doc, "id"), doc)
        if (x$length > 0) tdl[[counter]] <- meta(doc, "id")
        else tdl <- c(tdl, meta(doc, "id"))
        counter <- counter + 1
    }
    if (!is.null(x$names) && !is.na(x$names))
        names(tdl) <- x$names

    df <- data.frame(MetaID = rep(0, length(tdl)), stringsAsFactors = FALSE)
    filehash::dbInsert(db, "CorpusDMeta", df)
    dmeta.df <- data.frame(key = "CorpusDMeta", subset = I(list(NA)))

    .PCorpus(tdl, CorpusMeta(), dmeta.df, dbControl)
}

.VCorpus <-
function(x, meta, dmeta)
    structure(list(content = as.list(x), meta = meta, dmeta = dmeta),
              class = c("VCorpus", "Corpus"))

VCorpus <-
Corpus <-
function(x, readerControl = list(reader = x$defaultreader, language = "en"))
{
    stopifnot(inherits(x, "Source"))

    readerControl <- prepareReader(readerControl, x$defaultreader)

    if (is.function(readerControl$init))
        readerControl$init()

    if (is.function(readerControl$exit))
        on.exit(readerControl$exit())

    # Allocate memory in advance if length is known
    tdl <- if (x$length > 0)
        vector("list", as.integer(x$length))
    else
        list()

    if (x$vectorized)
        tdl <- mapply(function(elem, id)
                          readerControl$reader(elem, readerControl$language, id),
                      pGetElem(x),
                      id = if (is.null(x$names) || is.na(x$names))
                          as.character(seq_len(x$length))
                      else x$names,
                      SIMPLIFY = FALSE)
    else {
        counter <- 1
        while (!eoi(x)) {
            x <- stepNext(x)
            elem <- getElem(x)
            id <- if (is.null(x$names) || is.na(x$names))
                as.character(counter)
            else
                x$names[counter]
            doc <- readerControl$reader(elem, readerControl$language, id)
            if (x$length > 0)
                tdl[[counter]] <- doc
            else
                tdl <- c(tdl, list(doc))
            counter <- counter + 1
        }
    }
    if (!is.null(x$names) && !is.na(x$names))
        names(tdl) <- x$names
    df <- data.frame(MetaID = rep(0, length(tdl)), stringsAsFactors = FALSE)
    .VCorpus(tdl, CorpusMeta(), df)
}

`[.PCorpus` <-
function(x, i)
{
    if (!missing(i)) {
        x$content <- x$content[i]
        index <- x$dmeta[[1 , "subset"]]
        x$dmeta[[1 , "subset"]] <- if (is.numeric(index)) index[i] else i
    }
    x
}

`[.VCorpus` <-
function(x, i)
{
    if (!missing(i)) {
        x$content <- x$content[i]
        x$dmeta <- x$dmeta[i, , drop = FALSE]
    }
    x
}

`[<-.PCorpus` <-
function(x, i, value)
{
    db <- filehash::dbInit(x$dbcontrol[["dbName"]], x$dbcontrol[["dbType"]])
    counter <- 1
    for (id in x$content[i]) {
        db[[id]] <- if (identical(length(value), 1L))
            value
        else
            value[[counter]]
        counter <- counter + 1
    }
    x
}

.map_name_index <-
function(x, i)
{
    if (is.character(i))
        match(i, if (is.null(names(x))) meta(x, "id", "local") else names(x))
    else
        i
}

`[[.PCorpus` <-
function(x, i)
{
    i <- .map_name_index(x, i)
    db <- filehash::dbInit(x$dbcontrol[["dbName"]], x$dbcontrol[["dbType"]])
    filehash::dbFetch(db, x$content[[i]])
}
`[[.VCorpus` <-
function(x, i)
{
    i <- .map_name_index(x, i)
    lazyTmMap <- meta(x, tag = "lazyTmMap", type = "corpus")
    if (!is.null(lazyTmMap))
        .Call("copyCorpus", x, materialize(x, i))
    x$content[[i]]
}

`[[<-.PCorpus` <-
function(x, i, value)
{
    i <- .map_name_index(x, i)
    db <- filehash::dbInit(x$dbcontrol[["dbName"]], x$dbcontrol[["dbType"]])
    db[[x$content[[i]]]] <- value
    x
}
`[[<-.VCorpus` <-
function(x, i, value)
{
    i <- .map_name_index(x, i)
    # Mark new objects as not active for lazy mapping
    lazyTmMap <- meta(x, tag = "lazyTmMap", type = "corpus")
    if (!is.null(lazyTmMap)) {
        lazyTmMap$index[i] <- FALSE
        meta(x, tag = "lazyTmMap", type = "corpus") <- lazyTmMap
    }
    x$content[[i]] <- value
    x
}

# Update NodeIDs of a CMetaData tree
.update_id <-
function(x, id = 0, mapping = NULL, left.mapping = NULL, level = 0)
{
    # Traversal of (binary) CMetaData tree with setup of NodeIDs
    set_id <- function(x) {
        x$NodeID <- id
        id <<- id + 1
        level <<- level + 1
        if (length(x$Children)) {
            mapping <<- cbind(mapping, c(x$Children[[1]]$NodeID, id))
            left <- set_id(x$Children[[1]])
            if (level == 1) {
                left.mapping <<- mapping
                mapping <<- NULL
            }
            mapping <<- cbind(mapping, c(x$Children[[2]]$NodeID, id))
            right <- set_id(x$Children[[2]])

            x$Children <- list(left, right)
        }
        level <<- level - 1
        x
    }
    list(root = set_id(x), left.mapping = left.mapping, right.mapping = mapping)
}

# Find indices to be updated for a CMetaData tree
.find_indices <-
function(x)
{
    indices.mapping <- NULL
    for (m in levels(as.factor(CorpusDMeta(x)$MetaID))) {
        indices <- (CorpusDMeta(x)$MetaID == m)
        indices.mapping <- c(indices.mapping, list(m = indices))
        names(indices.mapping)[length(indices.mapping)] <- m
    }
    indices.mapping
}

#c2 <-
#function(x, y, ...)
#{
#    # Update the CMetaData tree
#    cmeta <- .MetaDataNode(0, list(merge_date = as.POSIXlt(Sys.time(), tz = "GMT"), merger = Sys.getenv("LOGNAME")), list(CMetaData(x), CMetaData(y)))
#    update.struct <- .update_id(cmeta)
#
#    new <- .VCorpus(c(unclass(x), unclass(y)), update.struct$root, NULL)
#
#    # Find indices to be updated for the left tree
#    indices.mapping <- .find_indices(x)
#
#    # Update the CorpusDMeta data frames for the left tree
#    for (i in 1:ncol(update.struct$left.mapping)) {
#        map <- update.struct$left.mapping[,i]
#        DMetaData(x)$MetaID <- replace(DMetaData(x)$MetaID, indices.mapping[[as.character(map[1])]], map[2])
#    }
#
#    # Find indices to be updated for the right tree
#    indices.mapping <- .find_indices(y)
#
#    # Update the CorpusDMeta data frames for the right tree
#    for (i in 1:ncol(update.struct$right.mapping)) {
#        map <- update.struct$right.mapping[,i]
#        DMetaData(y)$MetaID <- replace(DMetaData(y)$MetaID, indices.mapping[[as.character(map[1])]], map[2])
#    }
#
#    # Merge the CorpusDMeta data frames
#    labels <- setdiff(names(DMetaData(y)), names(DMetaData(x)))
#    na.matrix <- matrix(NA,
#                        nrow = nrow(DMetaData(x)),
#                        ncol = length(labels),
#                        dimnames = list(row.names(DMetaData(x)), labels))
#    x.dmeta.aug <- cbind(DMetaData(x), na.matrix)
#    labels <- setdiff(names(DMetaData(x)), names(DMetaData(y)))
#    na.matrix <- matrix(NA,
#                        nrow = nrow(DMetaData(y)),
#                        ncol = length(labels),
#                        dimnames = list(row.names(DMetaData(y)), labels))
#    y.dmeta.aug <- cbind(DMetaData(y), na.matrix)
#    DMetaData(new) <- rbind(x.dmeta.aug, y.dmeta.aug)
#
#    new
#}

c.Corpus <-
function(..., recursive = FALSE)
{
    args <- list(...)
    x <- args[[1L]]

    if(length(args) == 1L)
        return(x)

    if (!all(unlist(lapply(args, inherits, class(x)))))
        stop("not all arguments are of the same corpus type")

    if (inherits(x, "PCorpus"))
        stop("concatenation of corpora with underlying databases is not supported")

    if (recursive)
        Reduce(c2, args)
    else {
        args <- do.call("c", lapply(args, content))
        .VCorpus(args,
                 CorpusMeta(),
                 data.frame(MetaID = rep(0, length(args)),
                            stringsAsFactors = FALSE))
    }
}

c.TextDocument <-
function(..., recursive = FALSE)
{
    args <- list(...)
    x <- args[[1L]]

    if(length(args) == 1L)
        return(x)

    if (!all(unlist(lapply(args, inherits, class(x)))))
        stop("not all arguments are text documents")

    .VCorpus(args,
             CorpusMeta(),
             data.frame(MetaID = rep(0, length(args)),
                        stringsAsFactors = FALSE))
}

content.Corpus <-
function(x)
    x$content

`content<-.Corpus` <-
function(x, value)
{
    x$content <- value
    x
}

length.Corpus <-
function(x)
    length(content(x))

print.Corpus <-
function(x, ...)
{
    cat(sprintf(ngettext(length(x),
                         "A corpus with %d text document\n\n",
                         "A corpus with %d text documents\n\n"),
                length(x)))

    meta <- meta(x, type = "corpus")$value
    dmeta <- meta(x, type = "indexed")

    cat("Metadata:\n")
    cat(sprintf("  Tag-value pairs. Tags: %s\n",
                paste(names(meta), collapse = " ")))
    cat("  Data frame. Variables:", colnames(dmeta), "\n")

    invisible(x)
}

inspect <-
function(x)
    UseMethod("inspect", x)
inspect.PCorpus <-
function(x)
{
    print(x)
    cat("\n")
    db <- filehash::dbInit(x$dbcontrol[["dbName"]], x$dbcontrol[["dbType"]])
    show(filehash::dbMultiFetch(db, unlist(x)))
    invisible(x)
}
inspect.VCorpus <-
function(x)
{
    print(x)
    cat("\n")
    print(noquote(content(x)))
    invisible(x)
}

lapply.PCorpus <-
function(X, FUN, ...)
{
    db <- filehash::dbInit(X$dbcontrol[["dbName"]], X$dbcontrol[["dbType"]])
    lapply(filehash::dbMultiFetch(db, unlist(content(X))), FUN, ...)
}
lapply.VCorpus <-
function(X, FUN, ...)
{
    lazyTmMap <- meta(X, tag = "lazyTmMap", type = "corpus")
    if (!is.null(lazyTmMap))
        .Call("copyCorpus", X, materialize(X))
    lapply(content(X), FUN, ...)
}

writeCorpus <-
function(x, path = ".", filenames = NULL)
{
    filenames <- file.path(path,
      if (is.null(filenames))
          sprintf("%s.txt", as.character(meta(x, "id", "local")))
      else filenames)

    stopifnot(length(x) == length(filenames))

    mapply(function(doc, f) writeLines(as.character(doc), f), x, filenames)

    invisible(x)
}